AssetBundle（2）AssetBundle的加载和使用

四种加载方式

1，AssetBundle.LoadFromMemoryAsync           第一种从内存异步加载 IEnumerator

2，AssetBundle.LoadFromFileAsync                  第二种从本地异步加载 IEnumerator

3，WWW.LoadFromCacheOrDownload             第三种使用www来加载

4，UnityWebRequest                                          第四种使用UnityWebRequest

一、AssetBundle.LoadFromMemoryAsync

using System.Collections;using System.Collections.Generic;using System.IO;using UnityEngine;using UnityEngine.Networking;public class LoadAssetBundles : MonoBehaviour {    IEnumerator Start ()    {        string rootPath = Application.streamingAssetsPath;        string path = rootPath+ "/AssetBundles/cubewall.unity3d";        //AssetBundle ab1 = AssetBundle.LoadFromFile("AssetBundles/scenes/share.unity3d");        //第一种从内存异步加载 IEnumerator        AssetBundleCreateRequest request = AssetBundle.LoadFromMemoryAsync(File.ReadAllBytes(path));        yield return request;        AssetBundle ab = request.assetBundle;        AssetBundle assetBundleManifest = AssetBundle.LoadFromFile(rootPath+"/AssetBundles/AssetBundles");        AssetBundleManifest manifest = assetBundleManifest.LoadAsset<AssetBundleManifest>("AssetBundleManifest");        //foreach (string name in manifest.GetAllAssetBundles())        //{        //    Debug.Log(name);        //}        string[] dependencies = manifest.GetAllDependencies("cubewall.unity3d");        foreach (string str in dependencies)        {            print(str);            AssetBundle.LoadFromFile(rootPath+"/AssetBundles/" + str);        }        //实例化资源        GameObject wallPrefab = ab.LoadAsset<GameObject>("cubewall");        Instantiate(wallPrefab);        //AssetBundle.UnloadAllAssetBundles(true);    }}

二、AssetBundle.LoadFromFileAsync

using System.Collections;using System.Collections.Generic;using System.IO;using UnityEngine;using UnityEngine.Networking;public class LoadAssetBundles : MonoBehaviour {    IEnumerator Start ()    {        string rootPath = Application.streamingAssetsPath;        string path = rootPath+ "/AssetBundles/cubewall.unity3d";        ////AssetBundle ab1 = AssetBundle.LoadFromFile("AssetBundles/scenes/share.unity3d");                //第二种从本地异步加载 IEnumerator        AssetBundleCreateRequest request = AssetBundle.LoadFromFileAsync(path);        yield return request;        AssetBundle ab = request.assetBundle;        //AssetBundle ab = AssetBundle.LoadFromFile("AssetBundles/scenes/cubewall.unity3d");        AssetBundle assetBundleManifest = AssetBundle.LoadFromFile(rootPath+"/AssetBundles/AssetBundles");        AssetBundleManifest manifest = assetBundleManifest.LoadAsset<AssetBundleManifest>("AssetBundleManifest");        //foreach (string name in manifest.GetAllAssetBundles())        //{        //    Debug.Log(name);        //}        string[] dependencies = manifest.GetAllDependencies("cubewall.unity3d");        foreach (string str in dependencies)        {            print(str);            AssetBundle.LoadFromFile(rootPath+"/AssetBundles/" + str);        }        //实例化资源        GameObject wallPrefab = ab.LoadAsset<GameObject>("cubewall");        Instantiate(wallPrefab);        //AssetBundle.UnloadAllAssetBundles(true);    }}

三、WWW.LoadFromCacheOrDownload

using System.Collections;using System.Collections.Generic;using System.IO;using UnityEngine;using UnityEngine.Networking;public class LoadAssetBundles : MonoBehaviour {    IEnumerator Start ()    {        string rootPath = Application.streamingAssetsPath;        string path = rootPath+ "/AssetBundles/cubewall.unity3d";        ////AssetBundle ab1 = AssetBundle.LoadFromFile("AssetBundles/scenes/share.unity3d");        //第三种使用www来加载        while (!Caching.ready)        {            yield return null;        }        WWW www = WWW.LoadFromCacheOrDownload(@"file://E:\UnityProjects\Unity5.4\AssetBundleProjects\Assets\StreamingAssets\AssetBundles\AssetBundles\cubewall.unity3d", 1);        //WWW www = WWW.LoadFromCacheOrDownload(@"http://192.168.1.102/AssetBundles\cubewall.unity3d", 1);        yield return www;        if (!string.IsNullOrEmpty(www.error))        {            Debug.Log(www.error);            yield break;        }        AssetBundle ab = www.assetBundle;        AssetBundle assetBundleManifest = AssetBundle.LoadFromFile(rootPath+"/AssetBundles/AssetBundles");        AssetBundleManifest manifest = assetBundleManifest.LoadAsset<AssetBundleManifest>("AssetBundleManifest");        //foreach (string name in manifest.GetAllAssetBundles())        //{        //    Debug.Log(name);        //}        string[] dependencies = manifest.GetAllDependencies("cubewall.unity3d");        foreach (string str in dependencies)        {            print(str);            AssetBundle.LoadFromFile(rootPath+"/AssetBundles/" + str);        }        //实例化资源        GameObject wallPrefab = ab.LoadAsset<GameObject>("cubewall");        Instantiate(wallPrefab);        //AssetBundle.UnloadAllAssetBundles(true);    }}

四、UnityWebRequest

using System.Collections;using System.Collections.Generic;using System.IO;using UnityEngine;using UnityEngine.Networking;public class LoadAssetBundles : MonoBehaviour {    IEnumerator Start ()    {        string rootPath = Application.streamingAssetsPath;        string path = rootPath+ "/AssetBundles/cubewall.unity3d";        ////AssetBundle ab1 = AssetBundle.LoadFromFile("AssetBundles/scenes/share.unity3d");        //第四种使用UnityWebRequest        string url = @"file://E:\UnityProjects\Unity5.4\AssetBundleProjects\Assets\StreamingAssets\AssetBundles\cubewall.unity3d";        //string url = @"http://192.168.1.102/AssetBundles\cubewall.unity3d";        UnityWebRequest request = UnityWebRequest.GetAssetBundle(url);        yield return request.Send();        //AssetBundle ab = DownloadHandlerAssetBundle.GetContent(request);        AssetBundle ab = (request.downloadHandler as DownloadHandlerAssetBundle).assetBundle;        AssetBundle assetBundleManifest = AssetBundle.LoadFromFile(rootPath+"/AssetBundles/AssetBundles");        AssetBundleManifest manifest = assetBundleManifest.LoadAsset<AssetBundleManifest>("AssetBundleManifest");        //foreach (string name in manifest.GetAllAssetBundles())        //{        //    Debug.Log(name);        //}        string[] dependencies = manifest.GetAllDependencies("cubewall.unity3d");        foreach (string str in dependencies)        {            print(str);            AssetBundle.LoadFromFile(rootPath+"/AssetBundles/" + str);        }        //实例化资源        GameObject wallPrefab = ab.LoadAsset<GameObject>("cubewall");        Instantiate(wallPrefab);        //AssetBundle.UnloadAllAssetBundles(true);    }}

加载Manifests

        AssetBundle assetBundle = AssetBundle.LoadFromFile(manifestFilePath);        AssetBundleManifest manifest = assetBundle.LoadAsset<AssetBundleManifest>("AssetBundleManifest");        string[] dependencies = manifest.GetAllDependencies("assetBundle"); //Pass the name of the bundle you want the dependencies for.        foreach (string name in manifest.GetAllAssetBundles())        {            Debug.Log(name);        }        foreach (string dependency in dependencies)        {            AssetBundle.LoadFromFile(Path.Combine(assetBundlePath, dependency));        }

AssetBundle的卸载

卸载有两个方面
1，减少内存使用
2，有可能导致丢失

什么时候去卸载资源

AssetBundle.Unload(true)卸载所有资源，即使有资源被使用着

1，在关卡切换、场景切换

2，资源没被用的时候 调用
AssetBundle.Unload(false)卸载所有没用被使用的资源

个别资源怎么卸载

1，通过 Resources.UnloadUnusedAssets.

2，场景切换的时候

关于文件校验

CRC MD5 SHA1

相同点：

CRC、MD5、SHA1都是通过对数据进行计算，来生成一个校验值，该校验值用来校验数据的完整性。

不同点：

1. 算法不同。CRC采用多项式除法，MD5和SHA1使用的是替换、轮转等方法；
2. 校验值的长度不同。CRC校验位的长度跟其多项式有关系，一般为16位或32位；MD5是16个字节（128位）；SHA1是20个字节（160位）；
3. 校验值的称呼不同。CRC一般叫做CRC值；MD5和SHA1一般叫做哈希值（Hash）或散列值；
4. 安全性不同。这里的安全性是指检错的能力，即数据的错误能通过校验位检测出来。CRC的安全性跟多项式有很大关系，相对于MD5和SHA1要弱很多；MD5的安全性很高，不过大概在04年的时候被山东大学的王小云破解了；SHA1的安全性最高。
5. 效率不同，CRC的计算效率很高；MD5和SHA1比较慢。
6. 用途不同。CRC一般用作通信数据的校验；MD5和SHA1用于安全（Security）领域，比如文件校验、数字签名等。

结尾

1，依赖包重复问题
a，把需要共享的资源打包到一起
b，分割包，这些包不是在同一时间使用的
c，把共享部分打包成一个单独的包
2，图集重复问题
3，Android贴图问题
4，iOS文件处理重复fixed in Unity 5.3.2p2.

Unity Asset Bundle Browser tool

工具链接：http://pan.baidu.com/s/1slPrVaP 密码：zz80

直接放在Editor目录下即可，在unity编辑器导航栏Windows->AssetBundle Browser